Sensitivity of full-sky experiments to large scale cosmic ray anisotropies

Abstract

The two main advantages of space-based observation of extreme energy ($\gtrsim 5\times 10^{19}$ eV) cosmic rays (EECRs) over ground based observatories are the increased field of view and the full-sky coverage with nearly uniform systematics across the entire sky. The former guarantees increased statistics, whereas the latter enables a clean partitioning of the sky into spherical harmonics. The discovery of anisotropies would help to identify the long sought origin of EECRs. We begin an investigation of the reach of a full-sky space-based experiment such as EUSO to detect anisotropies in the extreme-energy cosmic-ray sky compared to ground based partial-sky experiments such as the Pierre Auger Observatory and Telescope Array. The technique is explained here, and simulations for a Universe with just two nonzero multipoles, monopole plus either dipole or quadrupole, are presented. These simulations quantify the advantages of space-based, all-sky coverage.

11 pages, 8 figures

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• Large scale distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory
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Cited by in corpus (1)

• Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers